Workpieces, including food products, are portioned or otherwise cut into smaller pieces by processors in accordance with customer needs. Also, excess fat, bone, and other foreign or undesired materials are routinely trimmed from food products. It is usually highly desirable to portion and/or trim the workpieces into uniform sizes, for example, for steaks to be served at restaurants or chicken fillets used in frozen dinners or in chicken burgers. Much of the portioning/trimming of workpieces, in particular food products, is now carried out with the use of high-speed portioning machines. These machines use various scanning techniques to ascertain the size and shape of the food product as it is being advanced on a moving conveyor. This information is analyzed with the aid of a computer to determine how to most efficiently portion the food product into optimum sizes. For example, a customer may desire chicken breast portions in two different weight sizes, but with no fat or with a limited amount of acceptable fat. The chicken breast is scanned as it moves on an infeed conveyor belt and a determination is made through the use of a computer as to how best to portion the chicken breast to the weights desired by the customer, with no or limited amount of fat, so as to use the chicken breast most effectively.
Portioning and/or trimming of the workpiece can be carried out by various cutting devices, including high-speed liquid jet cutters (liquids may include, for example, water or liquid nitrogen) or rotary or reciprocating blades, after the food product is transferred from the infeed to a cutting conveyor. Once the portioning/trimming has occurred, the resulting portions are off-loaded from the cutting conveyor and placed on a take-away conveyor for further processing or, perhaps, to be placed in a storage bin.
Portioning machines of the foregoing type are known in the art. Such portioning machines, or portions thereof, are disclosed in prior patents, for example, U.S. Pat. Nos. 4,962,568 and 5,868,056, which are incorporated by reference herein. Typically, the workpieces are first carried by an infeed conveyor past a scanning station, whereat the workpieces are scanned to ascertain selected physical parameters, for example, their size and shape, and then to determine their weight, typically by utilizing an assumed density for the workpieces. In addition, it is possible to locate discontinuities (including voids), foreign material, and undesirable material in the workpiece, for example, bones or fat in a meat portion.
The scanning can be carried out utilizing a variety of techniques, including a video camera to view a workpiece illuminated by one or more light sources. Light from the light source is extended across the moving conveyor belt to define a sharp shadow or light stripe line. When no workpiece is being carried by the infeed conveyor, the shadow line/light stripe forms a straight line across the conveyor belt. However, when a workpiece passes across the shadow line/light stripe, the upper, irregular surface of the workpiece produces an irregular shadow line/light stripe as viewed by a video camera directed downwardly at an angle on the workpiece and the shadow line/light stripe. The video camera detects the displacement of the shadow line/light stripe from the position it would occupy if no workpiece were present on the conveyor belt. This displacement represents the thickness (height) of the workpiece. The width of the workpiece is determined by the width of the irregular shadow line/light stripe. The length of the workpiece is determined by the length of belt travel that shadow lines/light stripes are created by the workpiece. In this regard, an encoder is integrated into the infeed conveyor, with the encoder generating pulses at fixed distance intervals corresponding to the forward movement of the conveyor.
The data and information measured/gathered by the scanning devices are transmitted to a computer, typically on board the portioning apparatus, which records the location of the workpiece on the conveyor as well as the shape and other parameters of the workpiece. With this information, the computer determines how to optimally cut or portion the workpiece at the portioning station, and the portioning may be carried out by various types of cutting/portioning devices.
Automatic portioning systems of food products, such as boneless chicken breasts, should be capable of cutting the products into uniform shape, weight, and other parameters as provided by their users. Oftentimes, the users have finished samples that exemplify the users' particular needs, such as a sample having a desired shape.
Some conventional portioning systems use fixed forms to portion products into a specific shape. A form is like a cookie cutter that is used to stamp out a particular shape, and then the cut piece is trimmed to a desired thickness by various types of knives. The use of forms is cumbersome, in that each form is usable to stamp out only one shape, and thus many forms are required for stamping out various shapes. Also, each form stamps out pieces only to a particular shape, without considering, for example, the resulting weight. Hand cutting is also available for portioning food products into particular shapes, but cutting the products into both uniform shape and uniform weight is very difficult.
Accordingly, a need exists for an improved portioning system, which is capable of cutting workpieces to a specific shape, and of growing, shrinking, or otherwise altering the shape in order to achieve one or more additional parameters such as weight. Preferably, such a portioning system permits a user to readily define the particular shape, and any other parameter, to which workpieces are to be portioned.
The general problem of workpiece portioning, and in particular food workpiece portioning, is to fit acceptable portions into highly variable workpieces and then cut them. The workpieces to be processed, including food workpieces, vary in every dimension, have random defects, and have areas of fat and cartilage that must be avoided. The thickness varies throughout each workpiece in addition to the average thickness varying from workpiece to workpiece.
Processors of the workpieces, for example meat workpieces, expect the portions to be of a narrow weight range, to maximize the number of portions they can sell without dissatisfying anyone. Their customers expect the meat portions to be of a specific shape or close enough to it with a fairly narrow thickness range so that standardized processing can occur, such as a cooking process that will yield uniformly cooked meat. If the meat is to be placed in a bun, it is expected that the plan-view area of the meat portion should be compatible with the bun rather than disappearing inside or hanging over the bun excessively. Also, it is undesirable that large pieces of fat or cartilage exist in a portion. Also, tears, holes, and other defects are unattractive in a portion as well.
These issues are sought to be addressed by the methods and systems discussed below.